Coupling devices of the general type disclosed herein are well known in the prior art; such devices are commonly referred to as synchronizers. Prior art synchronizers, though well known for their value in preventing clashing or grinding of gears or jaw clutches in transmissions, have an inherent bulkiness which precludes their use in some transmissions not specifically designed or redesigned to provide for their use. This bulkiness may manifest itself in the axial and/or radial dimensions of the synchronizer. When the axial extent of a synchronizer on a shaft is large, the axial spacing between gears on the shaft and gears meshing therewith must be increased, thereby requiring an increase in the transmission design length. When the radial extent of a synchronizer on a transmission shaft is large, it may interfere with the placement of a gear on another shaft of the transmission, thereby requiring an increase in the transmission design width and/or length. Such increases in the size of a transmission not only increases the total manufacturing cost of the transmission per se, but also may preclude the installation of, or increase the installation cost of, the transmission in some vehicles.